(1) Field of the Invention
The present invention relates to an Internet facsimile machine for sending a facsimile via e-mail and also relates to an image transmission method for execution by the machine.
(2) Description of the Related Art
Recent technology has introduced Internet facsimile machines capable of sending an image via e-mail over the Internet. The image transmission by Internet facsimile machines (also referred to simply as “FAX machines”) is carried out in the following manner. First, a FAX machine at a sending end reads a paper document using its image reader unit to generate image data, and then sends the image data as an attachment to an e-mail over the Internet, using its mail server. A FAX machine at a receiving end receives the e-mail using its mail server, and prints out the received image data using its printer unit.
Generally, mail servers on FAX machines and relay mail serves, which relay e-mail on the Internet, are restricted in terms of the permissible data size of e-mail they can send and receive. This restriction is imposed in order to avoid heavy traffic on the Internet due to transmission of a large amount of data at a time. Unfortunately, however, this arrangement causes the following problem. In an attempt to send a number of pages, image data of a relatively large size needs to be sent as an e-mail attachment. In the case where an e-mail with such an attachment exceeds the permissible size, the e-mail can not be sent or received.
In addition, such large-sized image data involves another problem. A receiving FAX machine may not have sufficient memory left for storing the e-mail or expanding the image data. In such a case, the FAX machine fails to print out the image data.
Turning to FAX machines capable of color image transmission, which are now in increasing demand, the problems mentioned above are even worse.
In order to avoid the problems, JP 10-322501-A and JP 2003-46702-A disclose techniques of transmitting image data representing a multi-page document as a plurality of e-mail attachments, thereby reducing the size of each e-mail. According to the techniques disclosed, the image data, which is generated on a page-by-page basis, is sequentially divided into pieces for every two or more pages in a manner that none of the pieces exceeds the permissible size that the receiving mail server can handle. Each piece of image data is then separately sent by a single e-mail. This is to facilitate the reconstituting of the faxed image, which would otherwise be complex due to the greater number of e-mails.
Yet, there still is a problem as follows. The admissible size is set individually for each mail server. Thus, even if an e-mail is generated so as not to exceed the admissible size set for the sending-end mail server, the e-mail may exceed the admissible size set for a relay mail server or receiving-end server. In that case, the e-mail can not be successfully transmitted to the receiving mail server. Furthermore, it is highly likely to receive only one e-mail with an attachment carrying image data of the last page or last few pages of a multi-page document, whereas the other e-mails fail to be delivered. This is because the image data of a multi-page document is sequentially divided into pieces from the beginning on a multiple-page basis. As a result, the last piece usually represents the last few pages or possibly the last one page of the document. Thus, an e-mail with an attachment carrying the last piece is smaller in size than the other e-mails.
Normally, however, it is the first page of the document that contains, as the cover page, important information for identifying the sender. Thus, from the information contained in the last page or last few pages, it is difficult to figure out who the sender is. Not knowing the sender, the recipient can not take any action, such as requesting re-sending of the facsimile, to attend the facsimile transmission failure. Yet, the sender hardly finds out that the facsimile transmission has failed because the operations for sending out the facsimile have been duly completed. With this being the situation, there is a demand for a FAX machine capable of reliably sending to the recipient, the image of a specific page which contains information for contacting the sender.